Provided by: libsvga1-dev_1.4.3-27ubuntu1_i386 bug

NAME

       vga_init - initialize svgalib library

SYNOPSIS

       #include <vga.h>

       int vga_init(void);

DESCRIPTION

       It  detects  the  chipset  and  gives up supervisor rights. This is the
       recommended  first   line   of   any   program   that   uses   svgalib.
       vga_setchipset(3) can be called before it to avoid detection.

       Svgalib  catches  a  bunch of signals that usually kill your program to
       restore textmode. If  you  catch  signal’s  before  calling  vga_init()
       svgalib  will  restore  textmode and prepare for shutdown and then call
       your handler routine. If you don’t want this, catch  the  signal  after
       calling vga_init and do not daisychain to svgalib’s original handler.

       WARNING!   svgalib  needs  two  signals  for it’s own purposes (that is
       managing console switches). To avoid problems  it  uses  the  otherwise
       unused  signals  SIGUSR1  and  SIGUSR2.   However,  this means that you
       cannot use them in your  program  by  any  means.  They  are  setup  by
       vga_init() as everything else is.

       Since  version  1.2.11  vga_init()  includes  code  to  hunt for a free
       virtual console on its own in case you are  not  starting  the  program
       from  one  (but  instead  over  a  network  or modem login, from within
       ’screen’ or an  ’xterm’).  Provided  there  is  a  free  console,  this
       succeeds if you are root or if the svgalib calling user own the current
       console. This is to avoid people not using the console  being  able  to
       fiddle  with  it.   On graceful exit the program returns to the console
       from which it was started.  Otherwise it remains in text mode at the VC
       which  svgalib allocated to allow you to see any error messages. In any
       case, any I/O the svgalib makes in text mode (after  calling  vga_init)
       will also take place at this new console.

       Alas, some games misuse their suid root priviledge and run as full root
       process. svgalib cannot detect this and allows Joe Blow User to open  a
       new  VC  on  the  console.  If  this  annoys  you  ROOT_VC_SHORTCUT  in
       Makefile.cfg allows you to disable allocating a new VC for root (except
       when  he  owns the current console) when compiling svgalib. This is the
       default (disabling the allocation for root).

       vga_init() returns a non-zero value in  case  of  errors.  As  of  this
       writing  it  will  return  -1  if  it is unable to allocate a graphical
       console. Otherwise, 0 is returned.

BUGS

       Svgalib versions prior to 1.2.11 had a security hole where it would  be
       possible  to regain root priviledges even after a vga_init() call. This
       is not necessarily a problem, but if  your  program  is  vulnerable  to
       buffer overflows and other attacks, an attacker may exploit this.

       However, prior to your call, your program will need to run setuid root,
       so you should be very careful. The ioperm library  by  Olaf  Titz  will
       allow  svgalib  programs  to run not setuid root. However, it gives all
       programs unlimited access to the hardware. Again,  a  malicious  person
       can  exploit this (albeit a bit more difficult) too.  Thus, in general,
       make your svgalib programs as secure as any setuid root program.

       Some programs may (accidently) rely on the  old  behaviour  (which  was
       probably  due  to  the author not knowing about saved uids (which might
       actually even not have existed in Linux at that time)). A line:

       security compat

       in the configuration file /etc/vga/libvga.conf will reinstate  the  old
       behaviour whereas

       security revoke-all-privs

       enables the (currently default) action.

SEE ALSO

       svgalib(7),   vga_setmode(3),  mouse_init(3),  vga_claimvideomemory(3),
       vga_ext_set(3),        vga_fillblt(3),        vga_getcurrentchipset(3),
       vga_getdefaultmode(3),    vga_getgraphmem(3),   vga_runinbackground(3),
       vga_runinbackground_version(3), vga_safety_fork(3),  vga_setchipset(3),
       vga_setchipsetandfeatures(3), vgagl(7), libvga.config(5),

AUTHOR

       This  manual  page  was  edited by Michael Weller <eowmob@exp-math.uni-
       essen.de>. The exact source of the referenced function as  well  as  of
       the original documentation is unknown.

       It is very likely that both are at least to some extent are due to Harm
       Hanemaayer <H.Hanemaayer@inter.nl.net>.

       Occasionally this might be wrong. I hereby asked to be excused  by  the
       original author and will happily accept any additions or corrections to
       this first version of the svgalib manual.